热处理对低W-W连接度W-Cu-Zn合金静、动态力学性能的影响

The effects of heat treatment on mechanical properties of W-Cu-Zn alloy with low W-W contiguity

摘要:

采用钨粉表面化学镀铜与SPS固相烧结两种工艺相结合的方法,制备出具有低W-W连接度特征及以黄铜作为粘结相的W-Cu-Zn合金,研究了热处理工艺对合金组织与性能的影响。微观分析表明所制备出的W-Cu-Zn合金中,钨颗粒均匀分布在黄铜粘结相中,粘结相为α相Cu-Zn固溶体。热处理后钨与黄铜粘结相的两相分布没有发生变化,但力学性能变化显著,经870℃随炉冷却热处理后,W-Cu-Zn合金硬度由143.8HV提高至172.3HV,准静态压缩加载时断裂强度由650MPa提高至750MPa,临界失效应变由0.18增大至0.26,静态力学性能显著提高。动态压缩加载时断裂强度由710MPa提高到900MPa,临界失效应变由0.24提高到0.4,动态力学性能显著提高。机理分析表明,热处理前W-Cu-Zn合金的黄铜粘结相中存在Zn元素分布不均的现象,经870℃随炉冷却热处理后黄铜粘结相中Zn元素分布的均匀性大幅度提高,这是合金力学性能提高的原因之一；此外,热处理后黄铜粘结相中形成了大量细小弥散分布的Cu₃Zn析出相,起到弥散强化作用,这是合金的强度显著提高的另一个原因。

Abstract:

W-Cu-Zn alloy with Cu-Zn matrix and low W-W contiguity was prepared by electroless copper plating combined with SPS solid-phase sintering processes. The influence of heat treatment on the microstructure and mechanical properties of the alloy was investigated. Microstructure analysis reveals that tungsten particles distributed in the Cu-Zn matrix phase homogeneously. The Cu-Zn matrix phase is α-phase solid solution. The distribution of tungsten particles and Cu-Zn matrix phase has not changed after the normalizing heat treatment. However, the mechanical properties of W-Cu-Zn alloy has has evidently improved after annealing heat treatment at 870℃ followed by furnace cooling. Under quasi-static compression, the strength of W-Cu-Zn alloy increases from 650 MPa to 750MPa, and the critical failure strain increases from 0.18 to 0.26. Under dynamic compression, the strength of W-Cu-Zn alloy increases from 710 MPa to 900MPa, and the critical failure strain increases from 0.18 to 0.26. The hardness increases from 143.8HV to 172.3HV. Mechanism analysis reveals that there are two factors contributing to improvement of the mechanical properties of W-Cu-Zn alloy. Firstly, the distribution of elenment Zn is unhomogeneously within the original W-Cu-Zn alloy. The specimen processed by annealing heat treatment at 870℃ followed by furnace cooling exhibites advantage of homogeneous distribution of Zn within the matrix. Secontlly, a large number of fine Cu₃Zn precipitates are formed uniformly in the Cu-Zn matrix phase of W-Cu-Zn alloy after annealing heat treatment at 870℃ followed by furnace cooling, which plays the role of dispersion strengthening.